Gun barrel



March 28, 1944. w BQRN 2,345,089

GUN BARREL Original Filed March 21, 1939 INVENTOR. WO/(LJQ /z/ @pgw Patented Mar. 28, 1944 Waldemar Born, Stuttgart, Germany; vested in the Alien Property Custodian Griginal application March 21', 1939, Serial No.. 263,256. Divided and this application January 4,1941, Serial No. 373,181. In Germany September 28, 1935 3 Claims.

This invention relates to a firearm and has particular reference .to a barrel for a bullet and barrel system in which the bullet or projectile is deformed during its passage through the bar- 'rel from a larger initial calibre or maximum diameter down to a smaller muzzle calibre,in order to increase the propelling fcrceimparted to the bullet.

This application is a division of my copending application Serial No. 263,256, filed March 21, 1939, for Barrel and bullet system, patented July '7, 1942, Patent No. 2,288,604.

It is an object of the present invention to provide a barrel in which the bullet irrespective of the large deforming forces acting upon it is only deformed in a predetermined ballistically favorable manner, without assuming any undesirable shape.

Another object of the invention is to provide a barrel which prevents the production of excessive gas pressures and ensures an efficient guiding and centering action on the cylindrical part of the bullet and high firing precision.

Still another object of the invention is to prevent inflation, swelling or jamming of the bullet and especially of its core due to the upsetting pressur exerted upon it by the powder gases.

With these and other objects in view, as may become apparent from the within disclosures, the invention consists not only in the structures herein pointed out and illustrated by the drawing, but includes further structures coming within the scope of what hereinafter may be claimed.

My improved firearm is adapted to be used with bullets of the type disclosed in said patent.

The character of the invention, however, may be best understood by reference to certain of its structural forms, as illustrated by the accompanying drawing in which:

Figs. 1 to are exaggerated fragmentary axial sections of embodiments of my novel barrel construction; Fig. 1 shows a barrel in which the tapered portions of the lands extend into the conical part of the barrel; Fig. 1a is an enlarged fragmentary View illustrating the extension of the rifiing lands into the conical portion of the barrel, Fig. 1b is a view similar to Fig. lot but showing a modification; Fig. 2 shows a barrel in which the lands extend further into the conical part of the barrel; Fig. 3 shows a barrel in which the conical portion has two different tapers, the maximum taper being immediately in front of the cartridge magazine or breech chamber; Fig. 4 shows a barrel in which the taper follows a curve, having its maximum taper near the breech chamber; and

Fig. 5 shows a barrel similar to Fi 4-, but with the maximum tape-r at the end of the conical part.

In order to obtain desired ballistic effect. with projectiles. such as described in said patent; the barrels from which the projectiles are; fired are constructedin the following manner.

The tapered part of the barrel between the breech chamber andthe cylindrical part. is made longer than with normal barrels (the length of the tapered part of which is about 3 to 5 calibre lengths), by an amount corresponding to the required deformation work so as to keep the gas pressure within the known limits, while the pitch or taper may be kept at the known figure, i. e., one depth of the rifling or grooves at 3 to 5 calibre lengths or 1:80 to 1:100. The tapered part is followed by a cylindrical guidance for the bullet. Instead of making the normal tapered part of the barrel longer it is also possible to provide a separate conical portion between the normal tapered portion and the cylindrical portion of the barrel. I prefer to make said conical part with a smooth unrifled bore in order to avoid any undue resistance offered against acceleration of the projectile in addition to the resistance due to the deformation work.

A barrel of this kind is shown in Fig. 1. The conical part it in this case begins right in front of the breech chamber l5 and bullet space I9 and has a maximum calibre corresponding to the maximum diameter of the outer jacket of the bullet I, from which it is tapered uniformly down to the diameter of the cylindrical end portion l6 of the barrel that corresponds to the diameter of the bullet after the outer jacket of same has been drawn out and depressed. The cylindrical portion It is rifled at ll and the lands taper off in the conical part i l, as represented in Fig. 10 over a distance H3, in a similar manner as with the conventional barrels.

Where the manufacturing tolerances to be admitted for the barrel and bullet calibre are large, it may be required that the rifling extends further into the conical part M by a distance 18', Fig. 2, and in some instances to a point near the bullet space I9, in order to ensure the required degree of firing precision. In this case, the lands are so formed, if possible, that the grooving or channelling work exerted with respect to the outer jacket is kept at a low rate. To this end, the lands may be formed to rise quite gradually from the inner walls of the barrel, as to their height and width as shown in Fig. 1a, or with a very small twist or without any initial twist, as

shown in Fig. 1b so as to assume only quite gradually their normal width and height and their final twist.

In order to ensure high resulting precision it is required that the front bulb of the outer jacket is guided and centered in the conical part of the barrel already after a very short travelling distance and while the rear bulb is still being guided in the breech chamber. In order to produce such early guiding action with larger working toler-' ances I may provide the conical portion of the bore in the barrel with a high initial taper in front of the bullet space I9, for example, in the manner shown in Fig. 3 in which a short conical connecting portion 20 of an increased taper or pitch is provided between the long conical part 44" of the barrel and the chamber l9.

Furthermore, it is contemplated that the con-' ical portion of the barrel bore may have a taper following a non-rectilinear, curved characteristic having its maximum taper or pitch near the breech chamber or near the muzzle end, as shown by way of example at 2! and 2| in Figs. 4 and 5, respectively, whereby the special features, more particularly the explosion speed, of the respective gun-powder may be met or a rapid initial acceleration of the bullet may be effected.

The portion of the barrel in which the first acceleration and deformation is imparted to the projectile is made without any twist of the rifling, as shown at 23 in Fig. 1b, in order to ensure that the outer jacket of the bullet shown in said patent will be drawn out smoothly and exactly in the direction of the axis of the projectile, whereby the resulting precision is enhanced.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a firearm, for co-operation with a projectile that is adapted to be deformed from a larger initial calibre to a substantially smaller calibre during ejection, a barrel having a cylindrical muzzle end portion, a conical portion located immediately in front of the bullet space and having a relatively high taper, and an intermediate conical portion connecting said two first named portions, said last named portion having a relatively low' taper, said muzzle portion being rifled and the lands of said rifling extending into 20 and being tapering off in said intermediate con- 

